Method and apparatus for forming the calibration chart for the underground fuel tanks

ABSTRACT

The invention relates to the method and apparatus for forming the calibration chart used to measure the amount of fuel inside the fuel tanks ( 1 ) which comprises at least one laser distance measurement device ( 2 ) positioned inside said fuel tank ( 1 ) and measuring the distance between itself and the inner wall of said fuel tank ( 1 ) at separate points, at least one main shaft ( 14 ) providing said distance measurement device ( 2 ) with rotational movement circularly in the direction of B through up to 360 degrees and in the upward-downward direction of A through up to 270 degrees and at least one inclinometer ( 4 ) positioned on the surface ( 9 ) and measuring the angle X between said fuel tank ( 1 ) and the ground on which it is located.

TECHNICAL FIELD

The invention relates to the determination of the fuel level and amountinside the underground liquid fuel tanks in the gas stations.

The invention relates in particular to forming the calibration chartsused in order to determine the fuel level and amount inside theunderground liquid fuel tanks in the gas stations, wherein the errormargin is minimized.

BACKGROUND OF THE INVENTION

In the gas stations, various methods are employed to measure the levelof oil inside the underground fuel tanks. Such methods may be carriedout manually by dipping the level measurement sticks in the tank, aswell as automatically with the help of the electronic measurementsensors placed into the tank.

In all the said methods, the calculation is made for the amount ofliters that the level measured in millimeters corresponds to. Saidcalculation is made using the calibration chart previously prepared forthe fuel tank. The calibration chart shows the height of the fuel insidethe tank and the volume value corresponding to the same. The height ofthe fuel inside the tank is calculated by means of the aforesaid methodsand it is proportioned with respect to the tank volume, in order todetermine the fuel amount (volume).

In order to perform this calculation accurately, the calibration chart(mm/It) of the fuel tank must be correct. Otherwise, the measuredmillimeter value will not yield the correct value in liters.

The calibration charts for the fuel tanks are generally drawn up duringthe production thereof. However, the chart is suitable for the idealconditions and when the tank is placed underground, it deviates fromsaid ideal conditions and the calibration chart of the tank becomeserroneous.

In this case, it is necessary to carry out the tank calibration again,in order to obtain an accurate result when the level measurement systemis installed in the tank or when a manual measurement is performed. Thisis a difficult and costly work.

In order to carry out the calibration, the fuel inside the tank isemptied and millimeter measurement is made by stage wise filling of thefuel. For this system, the equipment such as one or two fuel tankers andthe fuel transfer pump are used in the station and it may take hours tocomplete the calibration for one tank.

During said period of time, the operation of the station must be ceasedin a stage wise manner and no sale must be conducted. Manual calibrationis labor intensive and costly, in addition to its hindering the overallfunctioning of the station.

Another calibration method is carried out in an automatic manner bymeans of the calibration software and automation systems in the systemshaving the tank automation system and the pump automation system. Withthe automatic calibration initiated after the tanks are completelyfilled, the system compares the mm value it receives from the tankautomation to the amount of fuel sold at the pumps, to prepare thecalibration chart for the tank.

In order for this system to function accurately, it is necessary to waitfor the tanks to become completely empty and there must no interventionin the meantime; also, in order to form a correct and complete chart,one needs to wait for the tank to be filled and emptied for severaltimes.

In such automation systems, it is necessary to completely fill severaltimes the expensive tanks with an average capacity of 20.000 lt. Thissituation leads to a high cost and a long duration of time. Also, as thedurations become very long in the stations with a low rate of sale,difficulties are encountered in obtaining the correct results.

Today, in the PCT document no. WO2007078221 titled “the calibrationmethod and apparatus for the determination of the amount of liquidinside the tank”, the invention disclosed relates to measuring andcalibrating the fuel level inside a fuel tank by means of a fuel sensor.In said application, the amount of fuel inside the tank is measuredaccording to the calibration value that corresponds to said fuel level.

However, when said tank is placed in an area that is not smoothaccording to this practice, said fuel levels appear with a value belowor above the actual one with a certain inclination and the desiredactual amount of fuel may not be reached.

Similarly, the EPC application no. EP1603826 titled “the measurementsystem for the underground liquid fuel tanks in the gas stations”relates to the system, which measures the amount of the fuel withdrawnfrom the liquid fuel tanks located underground of the gas stations. Herethe measurement procedure is carried out by means of the turbine pumpdipped into the tank. Amount of the fuel drawn by the gas pump ismeasured, and thus the amount of the remaining fuel may be calculated.

Unfortunately, it is also necessary in this practice to wait until thecomplete emptying of the tanks and there must no intervention meanwhile,in order for the system to function accurately.

Further according to the state of the art, in the patent document no.US2003230141 titled “optical fuel level sensor”, the variation in thefuel level is determined by means of an electronic level detectionsensor.

Also in said practice, difficulties are encountered in eliminating theaforesaid disadvantages.

Due to the aforementioned disadvantages, the effort has been made insearch of an innovation in the calibration method used to measure thefuel amount in the liquid fuel tanks.

DESCRIPTION OF THE INVENTION

Based on the mentioned state of the art, the object of the invention isto propose a method, which, regardless of the angle at which the liquidfuel tank is placed on the ground, is capable of calibrating the actualvalue of the fuel amount inside the tank in a faster and more accuratemanner as compared to the other systems.

Another object of the invention is to propose a structure, whichprovides a much more accurate and realistic calibration owing to thelaser measurement instrument.

Another object of the invention is to propose a structure, which enablesthe calibration procedure to be carried out in a very short time and thecalibration chart to be prepared easily.

Another object of the invention is to propose a structure with a muchlower cost for the formation of the calibration chart.

Still another object of the invention is to provide that the calibrationchart is prepared by means of the formation of the 3D (threedimensional) space points via laser measurement inside the tank and of3D modeling of the inside of the tank.

Still another object of the invention is to make it possible to alsodetect the dents and shape distortions on the tank, which are notpossible to realize via the existing calibration systems, owing to theperformance of said 3D modeling.

Still another object of the invention is to propose a structure, whichdoes not hinder for extended periods of time the operation of the liquidfuel station where the calibration is carried out and does not cause thestation to suffer material loss, owing to the much faster performance ofthe calibration in a shorter time.

DESCRIPTION OF THE FIGURES

FIG. 1: Side view of the apparatus for forming the calibration chart forthe underground tanks.

REFERENCE NUMBERS

-   -   1. Fuel Tank    -   2. Laser Distant Measurement Device    -   3. Ray of the Laser Device    -   4. Inclinometer    -   5. Motor A    -   6. Motor B    -   7. Hole    -   8. Control Unit    -   9. Surface    -   10. Band or Gear System A    -   11. Band or Gear System B    -   12. Manhole    -   13. Tank Cover    -   14. Main Shaft    -   15. Ground Zone    -   16. Connection Cables    -   17. The Steel Protective Pipe    -   18. Computer    -   X—The angle that might form because of the tank's being not        perfectly parallel to the ground    -   A—Upward-Downward Rotation Axis of the Laser Device    -   B—Circular Rotation Axis of the Main Shaft

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to the method and apparatus for forming thecalibration chart used to measure the amount of fuel inside the fueltanks (1).

In FIG. 1, a side view of the apparatus for forming the calibrationchart used to measure the amount of fuel inside the fuel tanks (1)according to the invention is represented.

Said apparatus comprises the main components of the fuel tank (1) wherethe fuels are stored, the laser distance measurement device (2) locatedin said fuel tank (1), the inclinometer (4) that determines the anglebetween said tank and the ground, the main shaft (14) that provides saidlaser distance measurement device (2) with upward and circular movement,the motor A (5) that drives said main shaft (14) via band or gear systemA (10), the motor B (5) that drives said main shaft (14) via band orgear system B (10), the control unit (8) that controls said apparatusand the computer (18) where the information coming out of said controlunit (8) are collected and the calibration chart is prepared.

The method for forming the calibration chart used to measure the amountof fuel inside the fuel tanks (1) comprises the following steps:

-   -   Rotating via at least one main shaft (14) the laser distance        measurement device (2) located inside the fuel tank (1) up to        360 degrees in circular direction of B and up to 270 degrees in        the upward-downward direction of A, and determining its distance        from the inner walls of said fuel tank (1) for separate points,        with the help of the ray (3) of the laser device,    -   determining via at least one inclinometer (4) the angle X        between said fuel tank (1) and the plane on which it is located,    -   transmitting the distance values between the laser distance        measurement device (2) and the inner wall of the fuel tank (1)        measured at separate points and the value of the angle X as        measured by the inclinometer (4) to the computer, via at least        one control unit (8) and    -   forming the calibration chart using the obtained distance values        and the value of the angle X.

The calibration chart is prepared by means of the formation of the 3D(three dimensional) space points via laser measurement inside said fueltank (1) and of 3D modeling of the inside of the tank.

The height information obtained from level measurement sensors usingdifferent measurement techniques (magnetostrictive, ultrasonic,capacitive, etc.) indicates only the height of the liquid in mm from thebottom point of the tank.

Said apparatus, just as in a liquid level probe, is extended into thetank (1) preferably through a 2-inch hole (7) and again as in the liquidlevel probe, it is passed through said hole (7) and is mounted to thefuel tank (1).

Said main shaft (14) is passed through the manhole (12) and then saidhole (7) located on the tank cover (13), and is thus inserted to thefuel tank (1). The steel protective pipe (17) is positioned about themain shaft (14), in order to increase the strength of said main shaft(14) and protect the same against the external effects.

The fuel tank (1) is positioned inside a ground zone (15) at an angle ofX with respect to ground.

The inclinometer (4) located on the extension of the apparatus remainingabove the surface (9) is positioned to calculated the inclination angleof X of the tank (1) or the connection point, if any. This informationis later used for 3D calculations. Since the motor may not be insertedinto the fuel tank (1), two servo motors (5, 6) are located on the topsection of the surface (9).

The movements of said motors (5, 6) are transmitted to the laserdistance measurement device (2) located inside said fuel tank (1) viamain shaft (14). When said apparatus starts to operate, the main shaft(14) moves through 0 to 360 degrees in the direction of B. Said mainshaft (14) performs said circular movement via the band or gear system A(10), owing to the drive it receives from the motor A (5).

Similarly, the laser distance measurement device (2) moves preferablythrough 0 to 270 degrees in the direction of A. Said laser measurementdevice (2) provides said upward-downward movement owing to the band orgear system B (11) moving the main shaft (14) up and down by the drivereceived from the motor B (6).

Thus the laser distance measurement device (2) measures the distancefrom the point it is located to various points along the inner wall ofthe tank (1) up to 360 degrees in the horizontal and 270 degrees in thevertical position, with the help of the ray (3) of the laser device.

Said distance measurements carried out many times to different pointsare collected in a computer (18) and analyzed to calculate the actual 3dimensional shape of the tank. Moreover, the value of X showing theinclination of the tank (1) or the connection point with respect to theground, if any, is also used during these calculations.

The reason is that the liquid inside the tank to be measured alwaysstands perpendicularly to the gravitational axis of the earth. In otherwords, if there is an angle (1) in the tank, the liquid would stayparallel to the ground plane, not to the tank (1).

The control of the aforesaid apparatus may be provided via at least onecontrol unit (8). The control unit (8) communicates the measurementsconducted by said laser distance measurement device (2) and theinclinometer (4) to at least one computer (18), via the connectioncables (16).

Once all the data collection procedures are complete, said apparatus istaken out of the fuel tank and the liquid level measurement probe isfitted in its place. The obtained data are converted to the calibrationchart in the computer environment and now it is possible to convert theheight data coming from the liquid level probe into the liquid volumeinformation.

According to a different embodiment of the invention, the ultrasonicsensor is used as the laser distance measurement device (2).

According to a different embodiment of the invention, the ultravioletsensor is used as the laser distance measurement device (2).

According to a different embodiment of the invention, the ultra wideband sensor is used as the laser distance measurement device (2).

According to a different embodiment of the invention, the position ofsaid laser distance measurement device (2) in the apparatus may bechanged and it may be fixed to an upper position (so that the directionof the laser light is downwards). Similar to the movement capability ofsaid laser distance measurement device (2), a mirror set is used, whichis moved along with the apparatus. In this way, the distance is measuredby way of reflection from the mirror having the same movementcapability, instead of the sensor moving itself.

The protective scope of this application is determined in the section ofclaims and the scope may by no means be limited to the description aboveprovided only for exemplary purposes. It is obvious that a personskilled in the art may provide the innovation put forward by theinvention also by using the similar embodiments and/or apply thisembodiment to other fields with similar purpose used in the relevantart. Consequently, such embodiments would obviously lack the criteria ofinnovative step.

The invention claimed is:
 1. A method for determining calibration chartsused to determine a level and amount of fuel inside underground fueltanks (1) at gas stations comprising the steps of: rotating a laserdistance measurement device (2) located inside an empty underground fueltank (1) via at least one main shaft (14), said rotation being up to 360degrees in circular direction of B and up to 270 degrees in theupward-downward direction of A, determining distances of the laserdistance measurement device (2) from inner walls of said fuel tank (1)for separate points by use of a ray (3) of the laser device, determiningan angle X between said fuel tank (1) and a horizontal plane via atleast one inclinometer (4), transmitting the determined distancesbetween the laser distance measurement device (2) and the inner walls ofthe fuel tank (1) measured at separate points and the angle X asmeasured by the inclinometer (4) to a computer (18) via at least onecontrol unit (8) and determining by the computer (18) the calibrationchart of the fuel tank (1) using 3D three dimensional) space pointsdetermined from the transmitted distances and the angle X along with 3D(three dimensional) modeling of the inside of the tank.
 2. An apparatusfor determining the calibration charts used to determine a level andamount of fuel inside a fuel tank (1) placed in the ground at a gasstation, comprising: at least one distance measurement device (2)positioned inside an empty underground fuel tank (1) and adapted tomeasure the distance between said distance measurement device and theinner wall of said fuel tank (1) at separate points; at least one mainshaft (14) supporting said distance measurement device (2) withrotational movement circularly in a direction of B through up to 360degrees and in an upward-downward direction of A through up to 270degrees; and at least one inclinometer (4) positioned on the ground (9)and adapted to measure angle X between said fuel tank (1) and ahorizontal plane; and a computer for determining the calibrations chartsusing 3D (three dimensional) space points based on the distancesdetermined by the distance measurement device (2) and the angle Xmeasured by the inclinometer (4) along with 3D (three dimensional)modeling of the inside of the tank.
 3. A method for determining thecalibration charts according to claim 1 characterized in that the mainshaft (14), which rotates the laser distance measurement device (2)through up to 360 degrees in the circular direction of B is driven by atleast one band or gear system A (10).
 4. A method for determining thecalibration charts according to claim 3 characterized in that said bandor gear system A (10) is driven by at least one motor A (5).
 5. A methodfor determining the calibration charts according to claim 1characterized in that the main shaft (14), which rotates the laserdistance measurement device (2) through up to 270 degrees in theupward-downward direction of A receives said upward-downward movementfrom at least one band or gear system B (11).
 6. A method fordetermining the calibration charts according to claim 1 characterized inthat said main shaft (14) comprises at least one band or gear system B(11) located on above ground, said one band or gear system B (11)providing the laser distance measurement device (2) with rotationalmovement through up to 270 degrees in the upward-downward direction ofA, wherein said band or gear system B (11) is driven by at least onemotor B (6).
 7. A method for determining the calibration chartsaccording to claim 1 further comprising the steps of: moving said laserdistance measurement device (2) to a fixed upper position with laserlight directed downwards and moving at least one mirror set to directthe laser light to said separate points.
 8. An apparatus for determiningthe calibration charts used to determine a level and amount of fuelinside a fuel tank (1) placed in the ground at a gas station,comprising: at least one laser distance measurement device (2)positioned inside an empty underground fuel tank (1) and adapted tomeasure the distances between said laser distance measurement device andthe inner walls of said fuel tank (1) at separate points; at least onemain shaft (14) supporting said distance measurement device (2) withrotational movement circularly in a direction of B through up to 360degrees and in an upward-downward direction of A through up to 270degrees; at least one inclinometer (4) positioned on the ground (9) andadapted to measure angle X between said fuel tank (1) and a horizontalplane; and a computer for determining the calibration charts using 3D(three dimensional) space points based on the distances determined bythe distance measurement device (2) and the angle X measured by theinclinometer (4) along with 3D (three dimensional) modeling of theinside of the tank.
 9. An apparatus for determining the calibrationcharts according to claim 8 further comprising at least control unit (8)located above ground (9) adapted to communicate the value of the angle Xmeasured by said inclinometer (4) and the distances measured by saidlaser distance measurement device (2) to the computer (18).
 10. Anapparatus for determining the calibration charts according to claim 8characterized in that said main shaft (14) comprises at least one bandor gear system A (10) located above ground (9) and adapted to rotate thelaser distance measurement device (2) through up to 360 degrees in thecircular direction of B.
 11. An apparatus for determining thecalibration charts according to claim 8 characterized in that said mainshaft (14) comprises at least one band or gear system B (11) locatedabove ground (9) and adapted to rotate the laser distance measurementdevice (2) through up to 270 degrees in the upward-downward direction ofA.
 12. An apparatus for determining the calibration charts according toclaim 10 further comprising at least one motor A (5) positioned aboveground (9), which drives said band or gear system A (10).
 13. Anapparatus for determining the calibration charts according to claim 11further comprising at least one motor A (6) positioned above ground (9),which drives said band or gear system B (11).
 14. An apparatus fordetermining the calibration charts according to claim 8 furthercomprising at least one hole (7) through said tank (1) enabling saidmain shaft (14) to pass into said fuel tank (1) and accommodating saidmain shaft (14).
 15. An apparatus for determining the calibration chartsaccording to claim 8 further comprising at least one steel protectivepipe (17) around said main shaft (14) adapted to increase the strengthof said main shaft (14) and protect the main shaft against externaleffects.
 16. An apparatus for determining the calibration chartsaccording to claim 2, wherein an ultrasonic sensor is used as saiddistance measurement device (2).
 17. An apparatus for determining thecalibration charts according to claim 2, wherein a microwave sensor isused as said distance measurement device (2).
 18. An apparatus fordetermining the calibration charts according to claim 2, wherein anultra wide band sensor is used as said distance measurement device (2).19. An apparatus for determining the calibration charts according toclaim 2, wherein a radar sensor is used as said distance measurementdevice (2).